# stress vector variable calculation

 Register Blogs Members List Search Today's Posts Mark Forums Read December 11, 2020, 06:59 stress vector variable calculation #1 New Member   Join Date: Dec 2017 Posts: 2 Rep Power: 0 Hello! I want to calculate the shear stress for my 3D flow in a channel in the streamwise direction. To do so I used the code below. I can obtain the shear stress for any given volume by integrating the calculated stress tensor. However, I want to see the distribution of shear stress like any given variable i.e. the stress at each node. A couple of questions: 1) I've calculated tau for each node but i cannot find the variable for the normal vector. Would simply calculating, for example, {taux} x {Y Grid K Unit Normal} be appropriate for txy (t = stress vector)? 2) my fluid quantities are calculated in the cartesian x-direction but in curved channel areas I need them to be streamwise. I can adjust direction using the equation below, but i'm unsure how best to apply it to every node in a region. Currently, my method is A) select region using pick & select tool, B) value blank to just show region, C) calculate variable using the above equation. It feels a bit clunky and i'm unsure of the results (at least until 1 is sorted). Is there a better method? Equation for variable adjustment (t= stress vector): t =ρ(tzx cosθ + txy sin⁡θ) Code for calculating stress tensor: {D} = {dUdX} + {dVdY} + {dWdZ} {T11} = 0.00089 * (2 * {dUdX} - 2/3 * {D}) - {Pressure} {T12} = 0.00089 * ({dVdX} + {dUdY}) {T13} = 0.00089 * ({dWdX} + {dUdZ}) {T22} = 0.00089 * (2 * {dVdY} - 2/3 * {D})-{Pressure} {T23} = 0.00089 * ({dVdZ} + {dWdY}) {T33} = 0.00089 * (2 * {dWdZ} - 2/3 * {D}) - {Pressure} {taux} = {T11} * {X Grid K Unit Normal} + {T12} *{Y Grid K Unit Normal} + {T13} * {Z Grid K Unit Normal} {tauy} = {T12} * {X Grid K Unit Normal} + {T22} *{Y Grid K Unit Normal} + {T23} * {Z Grid K Unit Normal} {tauz} = {T13} * {X Grid K Unit Normal} + {T23} *{Y Grid K Unit Normal} + {T33} * {Z Grid K Unit Normal} Apologies if this has been asked previously - looked through the older posts and couldn't find anything.  Tags shear stress, tecplot, unit normal Thread Tools Search this Thread Show Printable Version Email this Page Search this Thread: Advanced Search Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules Similar Threads Thread Thread Starter Forum Replies Last Post SAtkins CFX 3 August 3, 2016 14:27 Dave442 CFX 36 July 12, 2016 04:12 Sae woong Kil CFX 2 December 4, 2008 17:59 Z Main CFD Forum 0 March 3, 2005 12:32 AB Siemens 6 November 15, 2004 04:41

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